<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    var arrayLike = {
      '0': 1,
      '1': 2,
      '2': 3,
      length: 3
    }
    var ary = Array.from(arrayLike, (item) => {
      return item * 2;
    })
    // 等价于：var ary = Array.from(arrayLike, item => item * 2)
    console.log(ary)
  </script>
</body>
</html>